1. Field of the Invention
Embodiments of the present invention relate to a method and apparatus for setting a detour path in a wideband high frequency wireless system using a centralized Media Access Control (MAC) protocol.
2. Description of the Related Art
In a wireless system using ultra wideband high frequency signals of 60 GHz or a THz band in order to provide a data rate of gigabit per second, a directional antenna may be used for a power efficiency. Therefore, frequency signals may have a strong straightness, or may have a strong offset by an obstacle due to a frequency distribution characteristic.
Due to the above frequency characteristic, only when a Line of Sight (LOS) is secured between a transmitter and a receiver, a smooth communication may be enabled. When the LOS is not secured due to a human being or an obstacle, a communication disconnection may occur.
Although the LOS is blocked for a relatively very short period of time, a communication error resulting from a signal blockage may cause a serious problem in transmitting data and video streaming at a high speed.
An Institute of Electrical and Electronics Engineers (IEEE) 802.15.3c standardization organization provides a diversity function using a plurality of transmit antennas and a function of acquiring an optimal transmission path through beamforming. However, when a signal is blocked by the human being or the obstacle, the communication error may be unavoidable due to characteristics of a high frequency signal such as a strong straightness and a high offset by an object.
Generally, in a system using a centralized Media Access Control (MAC) protocol, a piconet coordinator may provide a plurality of devices with time synchronization information and resource allocation information using a beacon message. Through this, data may be transmitted and be received between the plurality of devices, or between each of the devices and the piconet coordinator.
A time synchronization and a resource allocation may be performed by the piconet coordinator, based on a superframe.
The superframe may include a beacon period, a Contention Access Period (CAP), and a Channel Time Allocation Period (CTAP).
The beacon period denotes a period where a beacon message is transmitted by the piconet coordinator, and includes a superframe length, a length of the CAP and the CTAP, channel allocation information, and synchronization information.
In the CAP, data may be transmitted using a contention scheme according to a Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) scheme. The CTAP includes a plurality of CTA blocks so that a combination of a source device and a destination device may transmit and receive data without a contention.
Here, the CTA block may be formed in such a manner that a particular source device requests the piconet coordinator for a resource and receives a response to the request using a beacon message.
In the CTAP, the plurality of CTA blocks may be allocated by the piconet coordinator according to a Time Division Multiple Access (TDMA) scheme. A single CTA block or the plurality of CTA blocks for a combination of the particular source device and the destination device may be periodically allocated per a single superframe or per a plurality of superframes. Also, a predetermined number of CTA blocks may be allocated over the plurality of superframes.